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How to overcome this 2D -Transpose Matrix Index Out of Bound Exception in C# program

As you can see this is 2D transpose of matrix program, when executing this program it throws an index out of bound exception when it reached in some lines of code. Code raising exception is mentioned below.
C# Program
static void Main(string[] args)
{
Console.Write("No of Rows entered = ");
int r = Convert.ToInt32(Console.ReadLine());
Console.Write("No of Columns entered = ");
int c= Convert.ToInt32(Console.ReadLine());
int[,] arr1 = new int[r, c];
int[,] arr2 = new int[r, c];
for (int i = 0; i < r; i++)
{
for (int j = 0; j < c; j++)
{
Console.Write("[{0}],[{1}] : ", i, j+" ");
arr1[i, j] = Convert.ToInt32(Console.ReadLine());
}
}
Console.WriteLine("Matrix before Transpose:");
for (int i = 0; i < r; i++)
{
Console.WriteLine();
for (int j = 0; j < c; j++)
Console.Write("{0}", arr1[i, j]+" ");
}
```
**When it execute this lines of code it shows exception**
```
for (int i = 0; i < r; i++)
{
for (int j = 0; j < c; j++)
{
arr2[j, i] = arr1[i, j];
}
}
Console.WriteLine("Matrix after Transpose: ");
for (int i = 0; i < r; i++)
{
Console.WriteLine();
for (int j = 0; j < c; j++)
{
Console.Write("{0}", arr2[i, j]);
}
}
}
```
[Image of Exception appear while executing the program][1]
[1]: https://i.stack.imgur.com/6rNCg.png

The position of r and c should be changed in the definition of arr2:
int[,] arr2 = new int[c, r];
In the last for-loop, r and c should also be changed from position:
Console.WriteLine("Matrix after Transpose: ");
for (int i = 0; i < c; i++)
{
Console.WriteLine();
for (int j = 0; j < r; j++)
{
Console.Write("{0}", arr2[i, j]);
}
}

Check common elements of two-dimensional arrays of integers, considering the positions they are on

at the beginning I want to mention that I am a beginner in programming. So, I want to write a program that checks the similarity of two-dimensional arrays of integers. The similarity is to be determined by the amount of numbers that are in the same positions in both tables. The user gives the number of columns in the table and the elements themselves, number of rows is the same all the time.The similarity result is displayed as a percentage and the similarity itself should be calculated taking into account the number of elements of the larger array. My problem is: When the two arrays are the same size, the program throws the exception and it doesn't check all the numbers in the column.(I wrote before program for one dimensional array and it works perfectly) So far I have managed to write something like this:
This is what I want to do In the picture, the similarity between the arrays is 20%
{
Console.WriteLine("How extensive is the first table supposed to be?");
int n = int.Parse(Console.ReadLine());
int z = 2;
int[,] tab1 = new int[2, n];
Console.WriteLine("Enter the numbers into the first array:");
for (int i = 0; i < z; i++)
{
for (int j = 0; j < n; j++)
{
tab1[i, j] = int.Parse(Console.ReadLine());
}
}
Console.WriteLine("\n");
int rowLength = tab1.GetLength(0);
int colLength = tab1.GetLength(1);
for (int i = 0; i < rowLength; i++)
{
for (int j = 0; j < colLength; j++)
{
Console.Write(string.Format("{0} ", tab1[i, j]));
}
Console.Write(Environment.NewLine + Environment.NewLine);
}
Console.WriteLine("How extensive is the second table supposed to be?");
int m = int.Parse(Console.ReadLine());
int b = 2;
int[,] tab2 = new int[2, m];
Console.WriteLine("Enter the numbers into the second array: ");
for (int i = 0; i < b; i++)
{
for (int j = 0; j < m; j++)
{
tab2[i, j] = int.Parse(Console.ReadLine());
}
}
Console.WriteLine("\n");
int Len4gth = tab2.GetLength(0);
int Len2gth = tab2.GetLength(1);
for (int i = 0; i < Len4gth; i++)
{
for (int j = 0; j < Len2gth; j++)
{
Console.Write(string.Format("{0} ", tab2[i, j]));
}
Console.Write(Environment.NewLine + Environment.NewLine);
}
double similarity= 0;
if (tab1.GetLength(1) > tab2.GetLength(1))
{
for (int i = 0; i < tab2.GetLength(1); i++)
{
for (int j = 0; j < z; j++)
{
if (tab1[i, j] == tab2[i, j])
{
similarity+= 1;
}
}
}
}
if (tab1.GetLength(1) < tab2.GetLength(1))
{
for (int i = 0; i < tab1.GetLength(1); i++)
{
for (int j = 0; j < z; j++)
{
if (tab2[i, j] == tab1[i, j])
{
similarity+= 1;
}
}
}
}
if (tab1.GetLength(1) == tab2.GetLength(1))
{
for (int i = 0; i < tab1.GetLength(1); i++)
{
for (int j = 0; j < z; j++)
{
if (tab1[i, j] == tab2[i, j])
{
similarity+= 1;
}
}
}
}
if (tab1.Length < tab2.Length)
{
Console.WriteLine("The similarity of the arrays is: " + (similarity/ tab2.Length) * 100 + "%");
}
if (tab1.Length > tab2.Length)
{
Console.WriteLine("The similarity of the arrays is: " + (similarity/ tab1.Length) * 100 + "%");
}
if (tab1.Length == tab2.Length)
{
Console.WriteLine("The similarity of the arrays is: " + (similarity/ tab2.Length) * 100 + "%");
}
Console.ReadKey();

You must compare each element of the first array with the elements of the second array.
use this code :
//get first array items
Console.WriteLine("How extensive is the first table supposed to be?");
int n = int.Parse(Console.ReadLine());
int[,] tab1 = new int[2, n];
Console.WriteLine("Enter the numbers into the first array:");
for (int i = 0; i < 2; i++)
{
for (int j = 0; j < n; j++)
{
tab1[i, j] = int.Parse(Console.ReadLine());
}
}
Console.WriteLine("\n");
//write first array items
for (int i = 0; i < 2; i++)
{
for (int j = 0; j < n; j++)
{
Console.Write(string.Format("{0} ", tab1[i, j]));
}
Console.Write(Environment.NewLine + Environment.NewLine);
}
//get second array items
Console.WriteLine("How extensive is the second table supposed to be?");
int m = int.Parse(Console.ReadLine());
int[,] tab2 = new int[2, m];
Console.WriteLine("Enter the numbers into the second array: ");
for (int i = 0; i < 2; i++)
{
for (int j = 0; j < m; j++)
{
tab2[i, j] = int.Parse(Console.ReadLine());
}
}
//write second array items
Console.WriteLine("\n");
for (int i = 0; i < 2; i++)
{
for (int j = 0; j < m; j++)
{
Console.Write(string.Format("{0} ", tab2[i, j]));
}
Console.Write(Environment.NewLine + Environment.NewLine);
}
//find similarity items
double similarity = 0;
for (int i = 0; i < 2; i++)
{
for (int j = 0; j < n; j++)
{
int firstValue = tab1[i, j];
for (int k = 0; k < 2; k++)
{
for (int d = 0; d < m; d++)
{
if (firstValue == tab2[k, d])
{
similarity += 1;
}
}
}
}
}
double percentage = n > m ? ((similarity / tab1.Length) * 100) : ((similarity / tab2.Length) * 100);
Console.WriteLine("The similarity of the arrays is: " + percentage + "%");
Console.ReadKey();
this code work without error and It does not matter which array is larger.
If you want similar elements like this example enter link description here, use this code snippet to find similar elements
//find similarity items
double similarity = 0;
int z = n > m ? m : n;
for (int i = 0; i < 2; i++)
{
for (int j = 0; j < z; j++)
{
if (tab1[i, j] == tab2[i, j])
{
similarity += 1;
}
}
}
double percentage = n > m ? ((similarity / tab1.Length) * 100) : ((similarity / tab2.Length) * 100);
Console.WriteLine("The similarity of the arrays is: " + percentage + "%");
Console.ReadKey();

My code won't do the sum; only the elements of the matrix appear and then nothing happens

namespace Suma_diagonala_secundara
{
class Program
{
static void Main(string[] args)
{
int n, i, j, s = 0;
Console.Write("n= ");
n = Convert.ToInt32(Console.ReadLine());
int[,] tab = new int[n, n];
for(i=0;i<n;i++)
for (j = 0; j < n; j++)
{
Console.Write("tab[{0}][{1}]= ", i + 1, j + 1);
tab[i, j] = Convert.ToInt32(Console.ReadLine());
}
Console.Write("\nElementele matricii sunt: ");
for (i = 0; i < n; i++)
{
for (j = 0; j < n; j++)
Console.Write("{0} ", tab[i, j]);
Console.WriteLine("");
}
Console.WriteLine("Suma elementelor de pe diagonala secundara este: ");
for (i = 0; i < n; i++)
{
s = s + tab[i, n - i + 1];
}
Console.ReadKey();
}
}
}

In your loop
for (i = 0; i < n; i++)
{
s = s + tab[i, n - i + 1];
}
you are accessing the array out of bounds, since n - 0 + 1 = n + 1 is larger than n - 1 (the largest index in tab).
What you actually want is (note the parentheses)
for (i = 0; i < n; i++)
{
s = s + tab[i, n - (i + 1)];
}

The following line:
s = s + tab[i, n - i + 1];
Is throwing an IndexOutOfRangeException because you are requesting an index higher than the array capacity.
The correct loop code is (with decrement instead increment)
for (i = 0; i < n; i++)
{
s = s + tab[i, n - i - 1];
}

Why comma(",") is read as dot(".") string?

I have been trying to separate two numbers using "." but in Excel it sets ",". How can I fix it?
int col= 2;
for (int i = 0; i < proc; i++)
{
for (int j = 0; j < mac; j++)
{
wse.Cells[1, col] = (i + 1).ToString()+"." + (j + 1).ToString();
col++;
}
}

Change 2d array bubble sort to counting sort

The following code sorts rows by the first element using bubble method.
I can't change it to counting sort.
public void SortStack(double[,] n)
{
for (int i = 0; i < n.GetLength(0) - 1; i++)
{
for (int j = i; j < n.GetLength(0); j++)
{
if (n[i, 0] > n[j, 0])
{
for (int k = 0; k < n.GetLength(1); k++)
{
var temp = n[i, k];
n[i, k] = n[j, k];
n[j, k] = temp;
}
}
}
}
}
Please help.

As you do bubble sort based on first element of each row. you should do counting sort like that too. so you just need to count first item of each row.
private static int[,] CountingSort2D(int[,] arr)
{
// find the max number by first item of each row
int max = arr[0, 0];
for (int i = 0; i < arr.GetLength(0); i++)
{
if (arr[i, 0] > max) max = arr[i, 0];
}
// we want to get count of first items of each row. thus we need 1d array.
int[] counts = new int[max + 1];
// do the counting. again on first index of each row
for (int i = 0; i < arr.GetLength(0); i++)
{
counts[arr[i, 0]]++;
}
for (int i = 1; i < counts.Length; i++)
{
counts[i] += counts[i - 1];
}
// result is sorted array
int[,] result = new int[arr.GetLength(0), arr.GetLength(1)];
for (int i = arr.GetLength(0) - 1; i >= 0; i--)
{
counts[arr[i, 0]]--;
// now we need to copy columns too. thus we need another loop
for (int j = 0; j < arr.GetLength(1); j++)
{
result[counts[arr[i, 0]], j] = arr[i, j];
}
}
return result;
}
Here is the test.
static void Main()
{
Random rand = new Random();
int[,] arr = new int[3,3];
for (int i = 0; i < 3; i++)
{
for (int j = 0; j < 3; j++)
{
arr[i, j] = rand.Next(0, 100);
}
}
int[,] newarr = CountingSort2D(arr);
for (int i = 0; i < arr.GetLength(0); i++)
{
Console.Write("{ ");
for (int j = 0; j < arr.GetLength(1); j++)
{
Console.Write(arr[i, j] + " ,");
}
Console.Write("} ,");
}
Console.WriteLine();
for (int i = 0; i < newarr.GetLength(0); i++)
{
Console.Write("{ ");
for (int j = 0; j < newarr.GetLength(1); j++)
{
Console.Write(newarr[i, j] + " ,");
}
Console.Write("} ,");
}
Console.WriteLine();
}
Example Output:
{ 49,66,8 },{ 33,39,64 },{ 65,52,76 } // Original array
{ 33,39,64 },{ 49,66,8 },{ 65,52,76 } // Sorted array